Automatic damper



Nov. 3, 1931. c. A. TlERNBLOM AUTOMATIC DAMPER Filed NOV. 29. 1929Patented Nov. 3, 1931 UNITED STATES PATENT OFFICE AUTOMATIC DAMPERApplication filed November 29, 1929. Serial No. 410,873.

This invention relates to automatic damp- 'ers controlling the supply ofdraft air to forced draft furnaces, heaters, oil burners.

and the like. Automatic stokers are nowextensively used for supplyingthe fuel to coal furnaces. urnaces equipped with automatic stokers areusually of the underfeed type and a draft of air is forced to the firepot of the furnace generally by use of a blower. The blower, as a rule,is operated only while the stoker is 1n operation and the stoker isgenerally controlled by a thermostat to maintain .rooms, boilers or thelike to be heated at certain temperatures at different times of the day.With the present type of automatic stoker used, there is provided amanually controlled damper regulating the supply of air to the firepotfrom the blower. When the blower is in operation, it is usuallydesirable that the damper be opened widely to permit the free ingress ofthe air from the blower to the fire pot, and when the blower is not inoperation, it is desirable that the damper be closed to prevent thenatural draft of the fire and chimney from drawing in an oversupply ofair to the fire pot'. With the manually controlled damper, it isnecessary when the fire is banke-dfor the night, that the damper bemanually closed off or the natural draft of air will be so great thatthe fire will be almost completely burnt out before morning,

thereby wasting fuel and making it very difli cult to start the fireagain in the morning. It is also necessary for an attendant to open thedamper in the morning before the fire is started.

In forced draft oil burners when the blower or other air forcing meansis turned off, it is found that cold air will be drawn into the furnacedue to the draft of air in the chimney and this cold air acts to coolthe boiler and waste heat.

It is the objectof the present invention to provide in combination witha heating furnace,-and means for forcing a draft of air to the fire potthereof, an automatic damper which will act to close off the supplyofair to the fire pot, when the means for forcing the 0 air to the firepot is not in operation and will act to permit the free ingress of airto the fire pot when the means for forcing air thereto is in operation.

To this end, the invention consists in the novel parts and novelcombinations of parts, hereinafter defined in the claims and describedin the following'specification, made in connection with the accompanyingdrawings, wherein like reference charactersrefer to the same or similarparts through the various views and, in which,

Fig. 1 is a view taken chiefly invertical section through an underfeedheating furnace equipped with an automatic stoker having a blower forforcing a draft of air to the 5 fire pot of the furnace, the air inletport of the blower bein equipped with the automatic damper o the presentinvention;

Fig. 2is a plan view of the device illustrated in Fig. 1, certain of theparts being shown in section;

Fig. 3 is a View in side elevation illustrating the automatic damper ofthe present invention in detached relation;

Fig. 4 is a vertical section taken on the line 4-4 of Fig 3;

Fig. 5 is a horizontal section taken on the line 55 of Fig. 3, asindicated by the ar rows; and

Fig. 6 is an edge view of a clamping ring 80,

that may be used to hold the damper in place on the blower casing, aportion of the ring being shown in vertical section. Referring to thedrawings, portions ofan underfeed heating furnace A are illustratedwhich include a front wall 7 and a rear wall 8 constructed from brickand supporting grate bars 9 also carried by an underfeed fire pot 10.

A feed conduit 11-runs through the front wall 7 to'the fire pot 10, anda hopper 12 is connected to the outer end of the feed conduit 11 toproject upwardly therefrom. An electric motor 13 is supported at oneside of the hopper 12 and this motor is adapted to drive throughsuitable gearing (not illustrated) incased in a gear casing 14, a feedscrew 15 mounted in the feed conduit 11. An air conduit 16 for supplyinga draft of air to the fire pot 10 runs outwardly from the fire potthrough the front wall 7 of the furnace and is secured at its outer cndto the tangential discharge port of a blower 17 also adapted to bedriven through suitable gearing (not illustrated) in the gear casing 14from the motor 13. The blower 17 has a circular air inlet port 17 aformed at one side of the blower casing and, as is usual in suchconstructions, there is a hand operated damper 18 situated in the airconduit 16. The underfeed furnace thus far described is of standardconstruction and the automatic stoker also is of standard construction,the stoker illustrated being of the type now extensively sold under thetrademark Iron Fireman.

In accordance with the present invention, a disk 19 is provided having arectangular opening in its central portion through which the flangedinner end of a rectangular casing 20 extends. The flanges 20a of thecasing may be secured to the disk 19 as by rivets 21. J ournaled in theside walls of the casing 20, adjacent the outer open end thereof, aretwo horizontal shafts 22 and 23 respectively, the shaft 22 beingsituated adjacent the upper side 9f the casing and more closely adjacentthe open outer end of the casing than the shaft 23. The shaft 23 isdisposed approximately centrally relative to the height of the casing.Secured to the two shafts22 and 23 respectively, are upper and lowershutters 24 and 25, the said shutters being formed alike and preferablybeing composed from rectangular plates having their upper edges bentaround the shaft 22 or 23 to embrace the shafts and then riveted to themain portions of the plates. Weights 26 are carried adjacent the loweredges of the two shutters 24 and 25 and these weights, as best shown inFig. 5, will preferably be of laminated construction composed from aplurality of individual plates 26a. Nutted bolts 27 may be used forsecuring the weights 26in place on the shutters and it will be seen thatthe heaviness of the weights 26 may be variously adjusted by removing oradding additional plates 26a. The lower edge of the upper shutter 24 isdisposed inwardly from the shaft 23 and as the upper shutter is ofslightly greater width than the spacing between the two shafts 22 and23, the upper shutter will normally assume the position illustrated inFig. 4 with the lower edge of the upper shut-- ter bearing against theupper edge of the lower shutter, and with the upper shutter incliningsomewhat inwardly. The lower shutter 25 will normally hang verticallydownwardly from its shaft 23 to close off the lower half of the openingin the casing 20. The upper shutter 24 will normally, of course,

close off the upper half of the opening in the.

casing. The disk 19 is of such size that it will completely fit over theinlet port 17a at the side of the casing of the blower 17 and the diskmay be conveniently applied to the blower casing by means of a ring 28and screws 29,

the screws extending through suitable openings provided in the ring 28and disk 19.

The operation of the stoker in conjunction with the automatic damper ofthe present invention formed by the disk 19, casing 20, shafts 22 and23, shutters 24 and 25 and weights 26 will be as follows The manuallyoperated hand damper 18 will first be set to regulate the maximum amountof air that can be charged through the air conduit 16 when the blower 17is in operation. When the blower 17 is not in operation, the shutters 24and 25 will be held by gravity to practically completely close the airpassage to the blower through the casing 20 as shown in Fig. 4. Theweights 26 will be sufliciently heavy to hold the shutters 24 and 25 inclosed relation even though the heated coal B is burning strongly, thenatural draft of hot air up the chimney of the furnace beinginsufiicient to raise the shutters 24 and 25. \Vhen the blower 17 is setin operation. the pull of air through the opening in casing 20, will besnfliciently strong to raise the two shutters 24 and 25 to permit offree ingress of air from outside to the blower. If the blower 17 can beoperated at variable speeds as is customary in stokers of the typeillustrated, the shutters 24 and 25 will be raised varying amountsdepending on the speed of the blower. As the upper shutter 24, in itsnormal position, in-

clines somewhat inwardly toward the blower,

speeds, the lower shutter 25 may be raised somewhat, while the uppershutter 24 is still closed to permit opening of buta small passage-waythrough the casing 20 for the ingress of air, whereupon when the blower17 is operated at hi h speed, both shutters will be raised upwar ly toopen up a large passage through the casing 20 for the ingress of air tothe blower.

Green coal C will, of course, be supplied to the hopper 12 and this coalwill be fed into the fire pot 10 by means of the screw 15. When it is.desired to bank the fire for the night, a large quantity of green coalwill be fed to the fire pot. If the hand operated damper 18 was notadjusted to close off the supply of air through the air conduit 16 andthe automatic damper of the present invention was not used, the naturaldraft of air through the conduit 11 and the casing of the through saidcasing, said lower act to prevent the natural draft of the fire fromdrawing air through the conduit 16 and the casing of blower 17 toquickly burn the banker coal. In the morning when a heavy fire isrequired, it again becomes unnecessary to change the position of thehand controlled damper 18 to secure the heavy fire; lit is onlynecessary that the blower 17 be set in operation, whereupon the shutters2i and 25 of the automatic damper will quickly adjust themselves to openthe passage of air through the casing 20. When the present automaticdamper is used, the stoker can be entirely automatically operated, as bythermostatic control, and yet coal will not be wasted. lit will, ofcourse, be necessary to keep the hopper 12 of the stoker filled at alltimes. The present automatic damper acts as a fuel saver and eliminatesthe necessity for an attendant to go into the furnace room whenever itis desired to va'rythe heat of a furnace.

It will, of course, be understood that it is within the scope of thepresent invention to substitute a single shutter or a plurality ofshutters for the two shutters 24 and 25 illustrated. It is also possibleto provide other types of shutters than the type illustrated forcontrolling the size of the air passage to the blower automatically asthe blower is operated. The position of the automatic damper in theblower casing or in the air conduit can also bevaried without departurefrom the present invention.

holdingthe spaced shutter by ravit 0;

raise for some distance before said upper plate is raised, b

2. The combination with an air conduit and air forcing means, of adamper mounted in said conduit and comprising a pair of horizontallypivoted shutters mounted in said. conduit to extend across the same, oneabove the other, weights carried at the lower ends of said shutters andacting to normally hold said shutters by gravity in position to closesaid conduit, said shutters being adapted to raise to permit the travelof air through said conduit when said forcin means is in opera tion, oneof said shutters ein spaced slightly longitudinally of the con uitrelative to the other of said shutters and stop means for in normalposition inclined inwar the travel of air through said conduit, theother of said shutters normally being held by gravity in substantiallyvertical position, whereby as said air forcing means 1s set n operationthe vertically hanging shutter will raise for a short distance beforethe inclined shutter will raise.

In testimony whereof I rill my siature.

CHARLES A. TJERNB UM.

Although the automatic damper of the.

present invention is illustrated in connection with an underfeed coalheating furnace, it i can be equally as well applied to overhead feedcoal furnaces employing a forced draft, oil burning furnaces and heatersemploying a forced draft and other forced draft heating devices.

The present invention is of extremely simple construction andhas beensuccessfully demonstrated in actual practice.

It will, of course, be understood that vanous changes may be made in theform, details, arrangement and proportions of the various parts withoutdeparting from the scope of the present inventio What is claimed is2- 1. A damper comprising a supporting casng through which air isadapted to travel in one direction, an upper damper plate horizontallypivoted in said casing and extending across the same, a lowerdamperplate horizontally pivoted in said casing and extending across thesame, the pivot of said lower plate being slightly spaced from saidupper plate 1n the direction of travel of the air and said upper platenormally resting by gravity in inclined relation against the upperortion of I said lower plate, said lower plate eing normally held bygravity in substantially vertical position, whereby as air is forcedplate will ly re ative to

